Many optical systems using lens assemblies achieve acceptable optical performance with a standardized structure in which the lenses are supported on mounting surfaces in the lens housing. In this case, the housing and the lenses are manufactured to normal manufacturing tolerances, and the lenses are inserted into the housing and fixed in place without adjustment. On the other hand, high-performance optical assemblies having one or more lenses may require a level of optical performance beyond that achievable within normal manufacturing variations of the lenses and the lens housing. In this case, it may be necessary to axially adjust the positions of the lenses relative to each other during assembly in an iterative manner, until the required optical performance is achieved. The lenses are then fixed in place.
The usual approach for assembling such a high-performance optical system that requires adjustability during assembly is to assemble the lenses into the housing without fixing them in place, and then to check the optical performance. If it is determined that a lens must be moved axially to improve the optical performance, the axial movement is achieved by disassembling the assembly, and machining the mounting surface to move the lens in a first axial direction, or adding in a shim at the mounting surface to move the lens in a second axial direction opposite to the first axial direction. The lenses are reassembled in the housing, and the optical performance is rechecked. Axial re-adjustments are made as needed, and the process is repeated until the required optical performance is reached. The lenses are then permanently fixed to the housing.
This assembly and adjustment approach is often operable. However, it is slow, tedious, and uneconomic. It may also have significant technical problems. Upon each disassembly and reassembly, there may be a random error that introduces uncertainty as to whether the subsequent measurements and adjustments will be effective in producing the required optical performance. There is also a possibility of damage to the lenses or the housing at each disassembly/reassembly iteration.
There is a need for an improved approach to the assembly and optical adjustment of high-performance lens assemblies. The present invention fulfills this need, and further provides related advantages.